The present disclosure relates to a fuel vapor recovery apparatus to be mounted on a vehicle such as automobile.
This kind of fuel vapor recovery apparatus has a sealed tank system that usually seals a fuel tank with a high inner pressure in order to suppress the release of fuel vapor from the fuel tank. The fuel vapor recovery apparatus then depressurizes the fuel tank at the appropriate time (see, for example, Japanese Laid-Open Patent Publication No. 2005-307919). Depressurizing in the sealed tank system is normally carried out while the engine is running and during purge operation for allowing the flow of fuel vapor from a canister to an air intake system.
In Japanese Laid-Open Patent Publication No. 2005-307919, a solenoid valve is used as a blocking valve opening and closing a vapor path for providing communication between the fuel tank and the canister. The solenoid valve has an electromagnetic solenoid such that it is closed when current is not applied and it is open when current is applied. The blocking valve of the sealed tank system is usually composed of a solenoid valve.
In Japanese Laid-Open Patent Publication No. 2005-307919, in the opening period, the depressurizing volume is controlled by duty control of the solenoid valve. However, when the solenoid valve is used for the blocking valve, movement stroke of a valve body becomes large in order to ensure a flow path for smooth refueling. Thus, since duty control of the solenoid valve having a large stroke is carried out, depressurizing is intermittent, and a large amount of fluid flows through every opening of the valve, so that influence on air-fuel (A/F) ratio is large. Therefore, there has been a need for an improved fuel vapor recovery apparatus.